just think of it in terms of the violin family to give it a visual perspective. The amplification of acoustic instruments (as you should know) come form the body of the instruments. Each member of this family of instruments body's have over years been shape over and over to optimize the perspective sound to blend together. The tops are actually carved to a certain pitch (i believe Villon is F#).
so just think of a cello put on a Violin body it would be very silly not to mention hard to actually hear.
so while a bass amp may look somewhat the same whats going on in inside is very different.
ultimately, your playing them separate. record something you will immediately find out why you need a bass amp..... or you have really bad ears.
also I don't know you amp spec but you could potentially blow the cone.
telecrater says:
Then again maybe the bass through guitar amp is the tone your after and who am i to judge. But you did ask why your getting yelled at....
I second that in the end.
*added note* in case you think, "what about the acoustic bass guitar that's not that much bigger then the guitar they show me in me MTV. shouldn't they be playing the traditional acoustic bass?" The development that for only became relevant for MTV unplugged. It is visual crap-o-la, based of imagery for the modern rocker. Musically it is retarded and no serious musician that was any good in a non-pop sense would be caught dead with it, if they could avoid it anyway.